<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <link rel="stylesheet" href="demo.css">
    <script src="jquery.min.js"></script>
    <script src="demo.js"></script>
</head>
<body>
    <div class="selector open">
        <ul>
            <li>
                <input id="1" type="checkbox">
                <label for="1">unite</label>
            </li>
            <li>
                <input id="2" type="checkbox">
                <label for="2">unite</label>
            </li>
            <li>
                <input id="3" type="checkbox">
                <label for="3">unite</label>

            </li>
            <li>
                <input id="4" type="checkbox">
                <label for="4">unite</label>
            </li>
            <li>
                <input id="5" type="checkbox">
                <label for="5">unite</label>
            </li>
            <li>
                <input id="6" type="checkbox">
                <label for="6">unite</label>
            </li>
            <li>
                <input id="7" type="checkbox">
                <label for="7">unite</label>
            </li>
            <li>
                <input id="8" type="checkbox">
                <label for="8">unite</label>
            </li>
        </ul>
        <button>click</button>
    </div>
</body>
</html>